Continuously variable transmission belt and continuously variable transmission

ABSTRACT

A continuously variable transmission belt includes rings each superimposing annular component pieces on each other&#39;s inner and outer peripheries, and plural elements attached to the rings side by side in a circumferential direction. Each element includes a neck portion. The rings are disposed on opposite sides of the neck portion. The elements contact a driving pulley and a driven pulley. A lubrication oil discharge mechanism discharges out a lubrication oil in at least one of a gap between the component pieces, and a gap between each ring and the elements. A function of discharging the lubrication oil present in a region remote from the neck portion is higher than a function of discharging the lubrication oil present in a region near the neck portion. Thereby, the rings to which the elements are attached or the component pieces of the rings restrain decline in the centering characteristic in the width direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 12/516,607 filed May 28, 2009, the entire contentof which is incorporated herein by reference. U.S. application Ser. No.12/516,607 is a 371 application of PCT/IB07/03872 filed Dec. 12, 2007which claims priority to Japanese Patent Application No. 2006-336050filed Dec. 13, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a continuously variable transmission beltwrapped around a driving pulley and a driven pulley, and to acontinuously variable transmission having such a continuously variabletransmission belt.

2. Description of the Related Art

Generally, a transmission is provided on a power transmission path froma motive power source of a vehicle to wheels. As such a transmission, abelt type continuously variable transmission is known. This belt typecontinuously variable transmission is constructed by wrapping a belt ona driving pulley and a driven pulley, and performs power transmissionbetween the driving pulley and the driven pulley via the belt. Bycontrolling the wrap-around radii of the belt on the driving pulley andon the driven pulley, the continuously variable transmission controlsthe speed change ratio between the driving pulley and the driven pulley.An example of the driving belt used in the belt type continuouslyvariable transmission is described in Japanese Patent Publication No.2-22254. The driving belt described in Japanese Patent Publication No.2-22254 has a carrier made up of a band combination composed bysuperimposing endless bands on one another, and many metallic crossmembers that are slidably mounted on the carrier. Each cross member hasa neck portion, and two recesses are formed on both sides of the neckportion.

Incidentally, a lubrication device for a belt type continuously variabletransmission that has a continuously variable transmission belt isdescribed in Japanese Patent Application Publication No. 10-141459(JP-A-10-141459). In Japanese Patent Application Publication No.10-141459 (JP-A-10-141459), oil feed nozzles for supplying lubricationoil to the belt are disposed on both the input pulley side and theoutput pulley side. The belt has rings and elements. As the belt isdriven, relative sliding between the rings and the elements occur, sothat friction heat is generated on the contact surfaces. Therefore, bysupplying lubrication oil from the oil feed nozzles to the friction heatgenerating portions, the friction heat generating portions can belubricated, so that friction heat becomes relatively unlikely to begenerated.

In the case where the lubrication of the belt described in JapanesePatent Application Publication No. 10-141459 (JP-A-10-141459) isperformed in a belt type continuously variable transmission having abelt described in Japanese Patent Publication No. 2-22254, lubricationoil is not easily supplied deeply into the dents of the elements, thatis, to the vicinity of the neck portion of each element. Therefore, thefriction coefficient in the width direction of the carrier is higher inthe interior-depth side of each dent, that is, regions near the neckportions, than in regions apart from the neck portions. As a result,there is a possibility of decline in the centering performance of thecarrier in the width direction of the dents; for example, the line ofthe center of the carrier in the width direction may deviate from theline of the center of the driving belt in the width direction in a planeviewed from an outer periphery side of the carrier, or bandsconstituting the carrier tilt with each other.

SUMMARY OF THE INVENTION

This invention has been accomplished against the background of theaforementioned circumstances. The invention provides a continuouslyvariable transmission belt in which rings disposed in ring-receivingportions of individual elements are capable of restraining the declinein the widthwise centering characteristic at the ring-receivingportions, and a continuously variable transmission.

Accordingly, there is provided a continuously variable transmission beltthat has rings each constructed by superimposing annular componentpieces on each other's inner and outer peripheries, and a plurality ofelements stacked in a circumferential direction of the rings andattached to the rings, wherein each of the elements is provided with aneck portion extending in a radius direction of the rings, and each ofthe elements is provided with two ring-receiving portions on twoopposite sides of the neck portion in a width direction of the rings,and the rings are disposed in the two ring-receiving portions,respectively, and the elements contact a driving pulley and a drivenpulley, the continuously variable transmission belt being characterizedby including a lubrication oil discharge mechanism that discharges out alubrication oil that is in at least one of a gap between the annularcomponent pieces, and a gap between each ring and the elements, and thelubrication oil discharge mechanism has a construction in which afunction of discharging the lubrication oil present in a region that isremote from the neck portion in a width direction of the rings is higherthan a function of discharging the lubrication oil present in a regionthat is near the neck portion in the width direction of the rings.

According to the above-described continuously variable transmissionbelt, the belt has two rings constructed by superimposing annularcomponent pieces on each other's inner and outer peripheries, and aplurality of elements stacked in a circumferential direction of the tworings and attached to the rings. Each of the elements is provided with aneck portion extending in the radius direction of the rings. Besides,each of the elements is provided with two ring-receiving portions on thetwo opposite sides of the neck portion in the width direction of therings. The two rings are disposed in the two ring-receiving portions,respectively. Thus, the continuously variable transmission belt isconstructed. When the continuously variable transmission belt is wrappedaround the driving pulley and the driven pulley, the elements of thebelt contact the driving pulley and the driven pulley. Furthermore, whenlubrication oil is supplied and gets into the two ring-receivingportions, the lubrication oil enters the gaps between the two rings andthe elements and the gaps between the component pieces, thus restrainingheat generation. In this manner, when lubrication oil is supplied to thering-receiving portions, the supplied amount of lubrication oil islarger in a region that is apart from the neck portion in the widthdirection of the rings than in a region that is near the neck portion inthe width direction of the rings. This is because the path of passage oflubrication oil is shorter in the region that is apart from the neckportion in the width direction of the rings than in the region that isnear the neck portion in the width direction of the rings.

The lubrication oil that has got in either the gaps between thecomponent pieces or the gaps between the two rings and the elements orboth groups of gaps is discharged to the outside by the lubrication oildischarge mechanism. As for the lubrication oil discharge mechanism, thefunction of discharging out the lubrication oil present in a region thatis remote from the neck portion in the width direction of the rings ishigher than the function of discharging out the lubrication oil presentin a region that is near the neck portion in the width direction of therings. Therefore, in the width direction of the rings, the remainingamount of lubrication oil is equalized, so that the friction forces thatoccur on the mutual contact surfaces of the component pieces in thewidth direction or the friction forces that occur on the contactsurfaces of the rings and the elements are equalized. Therefore, in thering-receiving portions, the tilt of each ring in the width directionthereof or the tilt of the component pieces relative to each other isrestrained, so that the centering performance improves.

In the foregoing continuously variable transmission belt, it is alsopreferred that the lubrication oil discharge mechanism have a firstgroove provided on each of an inner periphery and an outer periphery ofthe annular component pieces, and a second groove provided on each ofthe elements, and that the function of discharging the lubrication oilpresent in the region that is remote from the neck portion in the widthdirection of the rings be made higher than the function of dischargingthe lubrication oil present in the region that is near the neck portionin the width direction of the rings by, in a plane on the rings viewedfrom an outer periphery side or an inner periphery side, making an areaof the first groove present in the region that is remote from the neckportion in the width direction of the rings larger than the area of thefirst groove present in the region that is near the neck portion in thewidth direction of the rings, and that the function of discharging thelubrication oil present in the region that is remote from the neckportion in the width direction of the rings be made higher than thefunction of discharging the lubrication oil present in the region thatis near the neck portion in the width direction of the rings by, in theplane on the rings viewed from the outer periphery side or the innerperiphery side, making the area of the second groove present in theregion that is remote from the neck portion in the width direction ofthe rings larger than the area of the second groove present in theregion that is near the neck portion in the width direction of therings.

According to the above-described continuously variable transmissionbelt, lubrication oil is discharged (thrown off) to the outside via thefirst groove and the second groove. This is because the kinetic energyof the lubrication oil adhering to the continuously variabletransmission belt is smaller than the kinetic energy of the continuouslyvariable transmission belt. In a plane on the rings viewed from theinner periphery side or the outer periphery side, the area of the firstgroove present in the region that is remote from the neck portion in thewidth direction of the rings is larger than the area of the first groovepresent in the region that is near the neck portion in the widthdirection of the rings. Therefore, in the gaps between the componentpieces constituting the rings, the amount of lubrication oil dischargedfrom the region that is remote from the neck portion in the widthdirection of the rings becomes larger than the amount of lubrication oildischarged from the region that is near the neck portion in the widthdirection of the rings. Besides, in the plane on the rings viewed fromthe outer periphery side or the inner periphery side, the area of thesecond groove present in the region that is remote from the neck portionin the width direction of the rings is larger than the area of thesecond groove present in the region that is near the neck portion in thewidth direction of the rings. Therefore, the amount of lubrication oildischarged from the region that is remote from the neck portion in thewidth direction of the rings becomes larger than the amount oflubrication oil discharged from the region that is near the neck portionin the width direction of the rings.

According to another aspect of the invention, there is provided acontinuously variable transmission belt that has a ring constructed bysuperimposing annular component pieces on each other's inner and outerperipheries, and a plurality of elements stacked in a circumferentialdirection of the ring and attached to the ring, wherein each of theelements is provided with an inward-side portion and a holder portionextending in a width direction of the ring from a neck portion extendingin a radius direction of the ring, and each of the elements is providedwith a ring-receiving portion between the inward-side portion and theholder portion in the width direction of the ring, and the ring isdisposed in the ring-receiving portion, and the elements contact adriving pulley and a driven pulley, the continuously variabletransmission belt being characterized by including a lubrication oildischarge mechanism that discharges out a lubrication oil that is in atleast one of a gap between the annular component pieces, and a gapbetween the ring and the elements, and the lubrication oil dischargemechanism has a construction in which a function of discharging thelubrication oil present in a region that is remote from the neck portionin a width direction of the ring is higher than a function ofdischarging the lubrication oil present in a region that is near theneck portion in the width direction of the ring.

According to the continuously variable transmission belt, each of theelements is provided with a ring-receiving portion between theinward-side portion and the holder portion in the width direction of thering. Then, the ring is disposed in the ring-receiving portion. Thus,the continuously variable transmission belt is constructed. When thecontinuously variable transmission belt is warped around the drivingpulley and the driven pulley, the elements contact the driving pulleyand the driven pulley. Furthermore, when lubrication oil is supplied andgets into the ring-receiving portion, the lubrication oil passes throughthe gap between the ring and the neck portion, and then is supplied intothe gaps between the ring and the elements and the gaps between thecomponent pieces, thus restraining heat generation. In this manner, whenlubrication oil is supplied to the ring-receiving portion, the suppliedamount of lubrication oil is larger in a region that is near the neckportion in the width direction of the ring than in a region that isapart from the neck portion in the width direction of the ring. This isbecause the path of passage of lubrication oil is shorter in the regionthat is near the neck portion in the width direction of the ring than inthe region that is apart from the neck portion in the width direction ofthe ring.

The lubrication oil that has got in either the gaps between thecomponent pieces or the gaps between the ring and the elements or bothgroups of gaps is discharged to the outside by the lubrication oildischarge mechanism. The amount of lubrication oil discharged from aregion that is remote from the neck portion in the width direction ofthe ring is larger than the amount of lubrication oil discharged from aregion that is near the neck portion in the width direction of the ring.Therefore, in the width direction of the ring in the ring-receivingportion, the remaining amount of lubrication oil is equalized, so thatthe friction forces that occur on the mutual contact surfaces of thecomponent pieces in the width direction or the friction forces thatoccur on the contact surfaces of the ring and the elements areequalized. Therefore, in the ring-receiving portions, the tilt of thering in the width direction thereof or the tilt of the component piecesrelative to each other is restrained, so that the centering performanceimproves.

In the foregoing continuously variable transmission belt, it is alsopreferred that the lubrication oil discharge mechanism have a firstgroove provided on each of an inner periphery and an outer periphery ofthe annular component pieces, and a second groove provided on each ofthe elements, and that a function of discharging the lubrication oilpresent in the region that is remote from the neck portion in the widthdirection of the ring is made higher than the function of dischargingthe lubrication oil present in the region that is near the neck portionin the width direction of the ring by, in a plane on the ring viewedfrom an outer periphery side or an inner periphery side, making an areaof the first groove present in the region that is near the neck portionin the width direction of the ring smaller than an area of the firstgroove present in the region that is remote from the neck portion in thewidth direction of the ring, and that the function of discharging thelubrication oil present in the region that is near the neck portion inthe width direction of the ring is made higher than the function ofdischarging the lubrication oil present in the region that is remotefrom the neck portion in the width direction of the ring by, in theplane on the ring viewed from the outer periphery side or the innerperiphery side, making an area of the second groove present in theregion that is near the neck portion in the width direction of the ringsmaller than an area of the second groove present in the region that isremote from the neck portion in the width direction of the ring.

According to the above-described continuously variable transmissionbelt, lubrication oil is discharged to the outside via the first grooveand the second groove. This is because the kinetic energy of thelubrication oil adhering to the continuously variable transmission beltis smaller than the kinetic energy of the continuously variabletransmission belt. Concretely, lubrication oil is discharged through thegaps between adjacent elements. In a plane on the ring viewed from theouter periphery side or the inner periphery side, the area of the firstgroove present in the region that is near the neck portion in the widthdirection of the ring is smaller than the area of the first groovepresent in the region that is apart from the neck portion in the widthdirection of the ring. Therefore, in the gaps between the componentpieces constituting the ring, the amount of lubrication oil dischargedfrom the region that is remote from the neck portion in the widthdirection of the ring becomes larger than the amount of lubrication oildischarged from the region that is near the neck portion in the widthdirection of the ring. Besides, in the plane on the ring viewed from theouter periphery side or the inner periphery side, the area of the secondgroove present in the region that is near the neck portion in the widthdirection of the ring is smaller than the area of the second groovepresent in the region that is apart from the neck portion in the widthdirection of the ring. Therefore, the amount of lubrication oildischarged from the region that is near the neck portion in the widthdirection of the ring becomes larger than the amount of lubrication oildischarged from the region that is apart from the neck portion in thewidth direction of the ring.

According to still another aspect of the invention, there is provided acontinuously variable transmission belt that has a ring constructed bysuperimposing annular component pieces on each other's inner and outerperipheries, and a plurality of elements stacked in a circumferentialdirection of the ring and attached to the ring, wherein each of theelements is provided with a ring-receiving portion, and the ring isdisposed in the ring-receiving portion, and the elements contact adriving pulley and a driven pulley, the continuously variabletransmission belt being characterized by including a friction forceequalization mechanism that makes a friction force that occurs due tocontact between a bottom surface that constitutes the ring-receivingportion and an inner peripheral surface of the ring uniform in the widthdirection of the ring.

According to the foregoing continuously variable transmission belt, theelements are stacked and attached to the ring. Thus the continuouslyvariable transmission belt is constructed. When the continuouslyvariable transmission belt is warped around the driving pulley and thedriven pulley, the elements contact the driving pulley and the drivenpulley. Besides, when lubrication oil enters the ring-receiving portionof each element, the friction force that occurs due to the contactbetween the bottom surface forming the ring-receiving portion and theinner peripheral surface of the ring is equalized in the width directionof the ring. Therefore, in the ring-receiving portions, the tilt of thering in the width direction thereof or the tilt of the component piecesrelative to each other is restrained, so that the centering performanceimproves.

In the foregoing continuously variable transmission belt, it is alsopreferred that each of the elements be provided with a neck portionextending in a radius direction of the ring, and each of the elements beprovided with two ring-receiving portions on two opposite sides of theneck portion in the width direction of the rings, and the ring bedisposed in each of the two ring-receiving portions, and the bottomsurface of each of the two ring-receiving portions and the innerperipheral surface of a corresponding one of the rings contact eachother, and that the friction force equalization mechanism be a partitiongroove that partitions each bottom surface into a first region near tothe neck portion and a second region apart from the neck portion, andthat prevent the lubrication oil from reaching the first region via thesecond region, and an area of the first region be smaller than the areaof the second region.

According to the foregoing continuously variable transmission belt, eachof the elements is provided with two ring-receiving portions on the twoopposite sides of the neck portion in the width direction of the rings,and the rings are disposed in the two ring-receiving portions,respectively. Then, the bottom surface forming each of the tworing-receiving portions is partitioned into the first region and thesecond region. The area of the first region is smaller than the area ofthe second region. Besides, lubrication oil is prevented from reachingthe first groove via the second groove. If the amount of lubrication oilis large, the friction coefficient becomes small. Therefore, thefriction force determined from area, friction coefficient, etc., becomessubstantially uniform between the first region and the second region, sothat the decline in the centering performance of the rings can berestrained.

In the foregoing continuously variable transmission belt, it is alsopreferred that each of the elements be provided with two neck portionsextending in a radius direction at different positions in the widthdirection of the ring, and a ring-receiving portion be provided betweenthe two neck portions, and the ring be disposed in the ring-receivingportion, and a bottom surface forming the ring-receiving portion and theinner peripheral surface of the ring contact each other, and that thefriction force equalization mechanism be a partition groove thatpartitions each bottom surface into two outer-side regions near to theneck portion and an inner-side region apart from the neck portion, andthat prevents the lubrication oil from reaching the inner-side regionvia the outer-side regions, and an area of the inner-side region besmaller than the area of one of the outer-side regions.

According to the foregoing continuously variable transmission belt, eachof the elements is provided with a ring-receiving portion between thetwo neck portions in the width direction of the ring, and the ring isdisposed in the ring-receiving portion. The bottom surface forming thering-receiving portion and the inner peripheral surface of the ringcontact each other. The bottom surface forming the ring-receivingportion is partitioned into the outer-side regions and the inner-sideregion. The area of the inner-side region is smaller than one of theouter-side regions. Besides, lubrication oil is prevented from reachingthe inner-side region via the outer-side regions. If the amount oflubrication oil is large, the friction coefficient becomes small.Therefore, the friction force determined from area, frictioncoefficient, etc., becomes substantially uniform between the inner-sideregion and the outer-side regions, so that the decline in the centeringperformance of the ring can be restrained.

According to a further aspect of the invention, there is provided acontinuously variable transmission that has a driving pulley, a drivenpulley, and a continuously variable transmission belt wrapped around thedriving pulley and the driven pulley, wherein the continuously variabletransmission belt has rings each constructed by superimposing annularcomponent pieces on each other's inner and outer peripheries, and aplurality of elements stacked in a circumferential direction of therings and attached to the rings, and each of the elements is providedwith a neck portion extending in a radius direction of the rings, andeach of the elements is provided with two ring-receiving portions on twoopposite sides of the neck portion in a width direction of the rings,and the rings are disposed in the two ring-receiving portions,respectively, the continuously variable transmission being characterizedby including an air blowing mechanism that blows air toward thering-receiving portions to move a lubrication oil present in eachring-receiving portion to an interior depth side of the ring-receivingportion so that in a plane on the continuously variable transmissionbelt viewed from an outer periphery side or an inner periphery side, adifference between a friction force on mutual contact portions of thecomponent pieces in a region that is near the neck portion in the widthdirection of the continuously variable transmission belt or a frictionforce that occurs on contact portions between an inner peripheralsurface of each ring and the elements (18), and a friction force onmutual contact portions of the component pieces in a region that isapart from the neck portion in the width direction of the continuouslyvariable transmission belt or a friction force that occurs on contactportions between the inner peripheral surface of each ring and theelements is made small.

It is also preferred that the continuously variable transmission beltwrapped around the driving pulley and the driven pulley be provided witha lubrication oil supply device that supplies the lubrication oil,between the driving pulley and the driven pulley, and that the airblowing mechanism be provided rearward of the lubrication oil supplydevice in a rotation direction of the continuously variable transmissionbelt. Furthermore, it is also preferred that the lubrication oil supplydevice and the air blowing mechanism be positioned between a point wherethe continuously variable transmission belt comes out of a wrapping onthe driven pulley and a point where the continuously variabletransmission belt becomes wrapped on the driving pulley, and supply thelubrication oil and blow air.

According to the foregoing continuously variable transmission, each ofthe elements is provided with ring-receiving portions, and the rings aredisposed in the ring-receiving portions. Thus the continuously variabletransmission belt is constructed. When the continuously variabletransmission belt is wrapped around the driving pulley and the drivenpulley, the elements contact the driving pulley and the driven pulley.Furthermore, lubrication oil is supplied to the ring-receiving portions,and the lubrication oil in each ring-receiving portion is moved to theinterior-depth side of the ring-receiving portion by blowing air towardeach ring-receiving portion in the rear of the lubrication oil supplydevice in the rotation direction. Due to this operation, in a plane onthe continuously variable transmission belt viewed from the outerperiphery side or the inner periphery side, a difference between thefriction force on mutual contact portions of the component pieces in aregion that is near the neck portion in the width direction of thecontinuously variable transmission belt or the friction force thatoccurs on contact portions between the inner peripheral surface of eachring and the elements, and the friction force on mutual contact portionsof the component pieces in a region that is apart from the neck portionin the width direction of the continuously variable transmission belt orthe friction force that occurs on contact portions between the innerperipheral surface of each ring and the elements becomes small.Therefore, in each ring-receiving portion, the tilt of the ring in thewidth direction thereof or the tilt of the component pieces relative toeach other is restrained, so that the centering performance improves.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, advantages, and technical and industrial significance ofthis invention will be better understood by reading the followingdetailed description of preferred embodiments of the invention, whenconsidered in connection with the accompanying drawings, in which:

FIG. 1 is a partial plan sectional view of a continuously variabletransmission belt in accordance with a first embodiment of theinvention, viewed from an outer periphery side;

FIG. 2 is a conceptual diagram showing a power train and its controlsystem of a vehicle that has a continuously variable transmission inaccordance with the invention;

FIG. 3 is a vertical sectional view of the continuously variabletransmission belt shown in FIG. 1, in a direction of the thickness ofthe belt;

FIG. 4 is a graph showing a friction coefficient characteristic of aring and a thin sheet that constitute the continuously variabletransmission belt;

FIG. 5 is a graph showing friction force characteristic of the rings andthe thin sheets that constitute the continuously variable transmissionbelt;

FIG. 6 is a graph showing a tension characteristic of the rings and thethin sheets that constitute the continuously variable transmission belt;

FIG. 7 is a graph showing a circumferential length of the rings and thethin sheets that constitute the continuously variable transmission belt;

FIG. 8 is a partial plan view showing a movement force characteristic ofthe rings and the thin sheets that constitute the continuously variabletransmission belt;

FIG. 9 is a vertical sectional view of a continuously variabletransmission belt in the width direction corresponding to a secondembodiment of the invention;

FIG. 10 is a partial plan sectional view of the continuously variabletransmission belt corresponding to the second embodiment of theinvention, viewed from the outer periphery side;

FIG. 11 is a vertical sectional view of a continuously variabletransmission belt in the width direction corresponding to a thirdembodiment of the invention;

FIG. 12 is a vertical sectional view of a continuously variabletransmission belt in the width direction corresponding to a fourthembodiment of the invention;

FIG. 13 is a vertical sectional view of a continuously variabletransmission belt in the width direction corresponding to a fifthembodiment of the invention;

FIG. 14 is a partial plan view of the continuously variable transmissionbelt corresponding to the fifth embodiment of the invention, viewed fromthe outer periphery side; and

FIG. 15 is a partial side view of the continuously variable transmissionbelt in the thickness direction corresponding to the fifth embodiment ofthe invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description and the accompanying drawings, theinvention will be described in more detail with reference to exemplaryembodiments.

A concept of a construction in which a continuously variabletransmission belt and a belt type continuously variable transmission ofthe invention are employed in a vehicle will be described. This belttype continuously variable transmission is disposed on a powertransmission path from a drive force source of the vehicle to wheelsthereof. This belt type continuously variable transmission has a drivingpulley and a driven pulley. The drive force source and the drivingpulley are interconnected so that power can be transmitted therebetween,and the driven pulley and the wheels are interconnected so that powercan be transmitted therebetween. The aforementioned vehicle may beeither a two-wheel drive vehicle or a four-wheel drive vehicle. That is,the vehicle may be either a two-wheel drive vehicle having a power trainconstructed so that power from the drive force source is transmitted toeither the front wheels (tire wheels) or the rear wheels (tire wheels),or a four-wheel drive vehicle having a power train constructed so thatthe power from the drive force source is transmitted to all of the frontwheels and the rear wheels. The four-wheel drive vehicle may be afull-time four-wheel drive vehicle in which power from the drive forcesource is transmitted to the front wheels and the rear wheels all thetime, or a standby four-wheel drive vehicle capable of switching betweena two-wheel drive state and a four-wheel drive state.

The drive force source is a power device that generates torque to betransmitted to the wheels. For example, it is possible to mount one ofor a combination of two or more of an engine, a motor-generator, ahydraulic motor, a fly wheel system, etc. in the vehicle. The engine isa device that converts thermal energy generated by combusting fuel intokinetic energy, and may be, for example, an internal combustion engine.The motor-generator is a power device equipped with both a power runningfunction of converting electric energy into kinetic energy and aregenerative function of converting kinetic energy into electric energy.The hydraulic motor is a device that converts fluid energy of ahydraulic oil into kinetic energy of a rotating member. The fly wheelsystem is a device capable of storing kinetic energy. That is, all ofthese power devices are different in the principle of power generation.

It is also possible to provide a clutch that controls the torquetransmitted between the drive force source and the wheels. This clutchmay be provided on either one of a path from the drive force source thedriving pulley and a path from the driven pulley to the wheels. Besides,the clutch is a power transmission device in which the transmissiontorque or the torque capacity can be controlled. For example, it ispossible to use an electromagnetic clutch, a fluid clutch, a frictionclutch, etc. Furthermore, it is possible to provide a forward-backwardtravel switch device on a power transmission path from the drive forcesource to the wheels. The forward-backward travel switch device is adevice that switches the rotation direction of an output-side rotatingmember relative to the rotation direction of an input-side rotatingmember between the normal and reverse directions, and may be provided oneither a path from the drive force source to the belt type continuouslyvariable transmission or a path from the belt type continuously variabletransmission to the wheels. The forward-backward travel switch devicemay be, for example, a planetary gear mechanism type forward-backwardtravel switch device, a parallel-axis gear type forward-backward travelswitch device, etc. In the continuously variable transmission belt ofthis invention, many elements are stacked and mounted in acircumferential direction of annular rings. Due to the compression forcegenerated between the elements, torque is transmitted between thedriving pulley and the driven pulley. Besides, the rings have functionsof a carrier, that is, functions of retaining a large number of elementsin an aligned state and retaining the elements so that the elements arerotatable relative to each other. In this invention, the driving pulleyis a pulley on the side where power is input, and is constructed so thattorque of the driving pulley is transmitted to the driven pulley via thebelt.

A power train and a control system of a vehicle that has a continuouslyvariable transmission to which various embodiments of the invention areapplied will be described with reference to FIG. 2. Firstly, a vehicle 1is equipped with a drive force source 2. A continuously variabletransmission, concretely, a belt type continuously variable transmission4, is disposed on a power transmission path from the drive force source2 to wheels 3. Incidentally, although it is possible to provide aforward-backward travel switch device on a path from the drive forcesource 2 to the belt type continuously variable transmission 4 or a pathfrom the belt type continuously variable transmission 4 to the wheels 3,such an arrangement is omitted from the illustration of this embodiment.Furthermore, although it is possible to provide a clutch on a path fromthe drive force source 2 to the belt type continuously variabletransmission 4 or a path from the belt type continuously variabletransmission 4 to the wheels 3, such an arrangement is omitted from theillustration of this embodiment. The belt type continuously variabletransmission 4 has a driving pulley 5 that is a first pulley, and adriven pulley 6 that is a second pulley. The driving pulley 5 and thedrive force source 2 are interconnected so that power can betransmitted.

The driving pulley 5 is constructed so as to rotate integrally with aninput shaft 7. This driving pulley 5 has a movable piece 8 that isactuatable in a direction parallel to the rotation axis of the inputshaft 7 (which direction is termed “axis direction”), and a stationarypiece 9 that is not actuatable in the axis direction. Besides, thedriven pulley 6 and the wheels 3 are interconnected so that power can betransmitted. Furthermore, the rotation axis (not shown) of the drivingpulley 5 and the rotation axis (not shown) of the driven pulley 6 aredisposed in parallel and substantially horizontally. The driven pulley 6is constructed so as to rotate integrally with an output shaft 10. Thedriven pulley 6 has a movable piece 11 that is actuatable in a directionparallel to the rotation axis of the output shaft 10 (which direction istermed “axis direction”), and a stationary piece 12 that is notactuatable in the axis direction. The driving pulley 5 and the drivenpulley 6 are each constructed so as to be able to adjust the groovewidth of the pulley by actuating the movable pieces 8, 11 in the axisdirection.

Furthermore, a hydraulic servo mechanism 13 that controls the positionof the movable piece 8 of the driving pulley 5 in the axis direction isprovided. The hydraulic servo mechanism 13 is a well-known mechanismthat has a hydraulic chamber, a piston, a return spring, etc. Besides, ahydraulic servo mechanism 14 that controls the position of the movablepiece 11 of the driven pulley 6 in the axis direction is also provided.The hydraulic servo mechanism 14 is a well-known mechanism that has ahydraulic chamber, a piston, a return spring, etc. An oil pressurecontrol device 15 is provided as an actuator that controls the oilpressure of the hydraulic chambers of the hydraulic servo mechanisms 13,14 or the amount of hydraulic oil supplied to the hydraulic chambers.That is, the belt type continuously variable transmission 4 is of ahydraulically controlled type. Incidentally, in the case where theaforementioned clutch is a fluid clutch or a friction clutch, it ispossible to adopt a construction in which the torque transmitted by theclutch is controlled by the oil pressure control device 15. The oilpressure control device 15 is a known device having a hydraulic circuit,a valve, etc., and is controlled by an electronic control device 100.Besides, in the case where the forward-backward travel switch device isprovided, it is possible to use the oil pressure control device 15 as anactuator of the forward-backward travel switch device. An annularcontinuously variable transmission belt is wrapped around the drivingpulley 5 and the driven pulley 6. Furthermore, a lubrication oil supplydevice 50 is connected to the oil pressure control device 15 via an oilpassageway. This lubrication oil supply device 50 supplies lubricationoil to heat-generating portions and sliding portions of the belt typecontinuously variable transmission 4 so as to cool and lubricate theseportions. The lubrication oil supply device 50 has a valve, a jetnozzle, etc. The lubrication oil supply device 50 is constructed to becontrolled by the electronic control device 100. The lubrication oilsupply device 50 is capable of adjusting a lubrication oil supplytiming, a lubrication oil supply duration, a lubrication oil supplyamount, a lubrication oil supply pressure (jet pressure), a lubricationoil supply angle with respect to the belt 16, etc. Hereinafter, concreteconstruction examples of the continuously variable transmission beltwill be sequentially described.

A first embodiment will be described with reference to FIGS. 1 and 3.FIG. 1 is a partial plan sectional view of a continuously variabletransmission belt (hereinafter, simply termed the belt) 16, viewed froman outer periphery side. FIG. 3 is a vertical sectional view (frontvertical sectional view) of the belt 16 in a thickness directionthereof. The belt 16 has two rings 17 and a plurality of (many) elements18 attached to the two rings 17. The many elements 18 are formed througha press process of a metal material. The elements 18 are attached to thetwo rings 17 and juxtaposed in a circumferential direction of the rings17. In the circumferential direction of the rings 17, adjacent elements18 are in contact with each other. Each element 18 has a base portion(plate-shape portion) 19 disposed along the width direction of the belt16, a neck portion 20 being continuous from the base portion 19 andprotruded to an outward side in a radius direction of the belt 16, and aholder portion 21 being continuous from the neck portion 20 and disposedalong the width direction of the belt 16. The holder portion 21 isprotruded from an upper end of the neck portion 20 to both sides in thewidth direction of the belt 16. That is, the neck portion 20 is aportion connecting the base portion 19 and the holder portion 21. Thewidth direction of the belt 16 means a direction of substantially alongthe width direction of the belt 16, or a direction parallel to the widthof the belt 16. Contact surfaces 22 are formed on two opposite ends ofthe base portion 19 in the width direction of the belt 16. Each of thetwo contact surfaces 22 of each element 18 is titled with respect to aline of the center (not shown) of the element 18 in the width directionof the belt 16 so that the distance between the two contact surfaces 22in the width direction of the belt 16 becomes shorter toward an innerperiphery side of the belt 16. The belt 16 is wrapped around the drivingpulley 5 and the driven pulley 6, and the contact surfaces 22 of theelements 18 contact the driving pulley 5 and the driven pulley 6 asshown in FIG. 3.

A protruded pin 18A is provided on one of two sides of an upper portionof each element 18 in the thickness direction. A recess 18B is providedon the other side of the upper portion of each element 18 in thethickness direction. When the elements 18 are superimposed on oneanother in the thickness direction, the pins 18A of elements 18 aredisposed in the recesses 18B of the adjacent elements 18A, wherebyelements 18 disposed at adjacent positions are defined in positionrelative to each other, concretely, defined in position relative to eachother on a plane orthogonal to the stacking direction of the elements18. In the width direction of the belt 16, the length (width) of thebase portion 19 is longer than the length (width) of the holder portion21. Due to this construction, each element 18 is provided withring-receiving portions 23 between the base portion 19 and the holderportion 21 in a radius direction of the belt 16 (an inner-to-outerperiphery direction thereof). Concretely, the radius direction of thebelt 16 means the same direction as the radius direction of the belt 16,or a direction substantially along the radius direction. Upper endsurfaces (surfaces) 24 of the base portion 19 are substantially flat,and the flat upper end surfaces 24 form bottom surfaces of thering-receiving portions 23. Specifically, two upper end surfaces 24 areprovided on both sides of the neck portion 20 in the width direction ofthe belt 16. Each upper end surface 24 is provided with a lubricationoil discharge mechanism that discharges the lubrication oil presentbetween the upper end surface 24 and the ring 17, to the outside of thering-receiving portion 24.

In the first embodiment, grooves 25 are provided as a lubrication oildischarge mechanism. The grooves 25 are recesses or dents having a depthin the radius direction of the belt 16 in FIG. 3, and also are in acheckered pattern formed by intersecting linear grooves 25 with eachother in FIG. 1. Besides, as shown in FIG. 1, the density of the grooves25 is different between a region A1 and a region B1 that are provided atdifferent positions on each upper end surface 24 in the width directionof the belt 16. On each upper end surface 24, the region A1 is disposedon an interior depth side of the ring-receiving portion 23 in the widthdirection of the belt 16, and the region B1 is disposed on an entranceside of the ring-receiving portion 23 in the width direction of the belt16. In other words, on each upper end surface 24, the region A1 is at aposition that is relatively near the neck portion 20, and the region B1is at a position that is apart from the neck portion 20. Furthermore, ina plan view of the belt 16 taken from the outside thereof, the positionof the region A1 substantially overlaps with the position of the holderportion 21. Then, in each upper end surface 24, the density of thegrooves 25 provided in the region B1 is higher than the density of thegrooves 25 provided in the region A1. Specifically, while the regionsA1, B1 are both provided with plural grooves 25 parallel to each other,the intervals between the grooves 25 provided in the region B1 areshorter than the intervals between the grooves 25 provided in the regionA1. In other words, the density of the grooves 25 per unit area in theregions B1 is higher than the density of the grooves 25 per unit area inthe regions A1. That is, the area of the grooves 25 per unit area in theregions B1 is larger than the area of the grooves 25 per unit area inthe regions A1.

Next, the construction of the two rings 17 will be described. Each ring17 is constructed by layering a plurality of metal-made annular thinsheets 26 on each other's inner and outer peripheries, that is, in theinner-to-outer periphery direction. That is, the thin sheets 26 aresuperimposed on one another in the thickness direction to construct aring 17. Besides, the thin sheets 26 in the superimposed state areslidable relative to one another in the circumferential direction.Besides, the thin sheets 26 have the same width in the width directionof the belt 16. In the width direction of the belt 16, the width of theindividual thin sheets 26 is narrower than the width of each of theupper end surfaces 24 of the elements 18. The many elements 18 areattached to the rings 17 constructed as described above. Concretely,each ring 17 is disposed in a corresponding one of the ring-receivingportions 23. When each ring 17 has been received in a corresponding oneof the ring-receiving portions 23 of each element 18, a substantiallyhalf of the ring 17 in the width direction of the belt 16 is positionedinside the ring-receiving portion 23, and the other half of the ring 17is positioned (exposed) outside the ring-receiving portion 23. That is,in the width direction of the belt 16, the width of each ring 17 islarger than the width of each ring-receiving portion 23. Incidentally,the width (height) of the ring-receiving portions 23 in the radiusdirection of the belt 16 is constant, and the thickness of the rings 17is less than the width (height) of the ring-receiving portions 23.Therefore, the elements 18 are slidable relative to the rings 17 in thecircumferential direction of the rings 17.

At least one of inner and outer peripheral surfaces of each of the thinsheets 26 constituting each ring 17 is provided with grooves 27 as alubrication oil discharge mechanism. The grooves 27 are recesses ordents having a depth in the thickness direction of each thin sheet 26.In FIG. 1, the grooves 27 are provided on the outer peripheral surfaceof each thin sheet 26 as an example construction. Concretely, acheckered pattern is formed by intersecting linear grooves 27 with eachother. Besides, as shown in FIG. 1, the density of grooves 27 isdifferent between a region C1 and a region D1 that are disposed atdifferent positions on each thin sheet 26 in the width direction of thebelt 16. On each thin sheet 26, the region C1 is disposed on an interiordepth side of the ring-receiving portion 23 in the width direction ofthe belt 16, and the region D1 is disposed on an entrance side of thering-receiving portion 23 in the width direction of the belt 16. Inother words, on each thin sheet 26, the region C1 is closer to the neckportion 20, and the region D1 is more apart from the neck portion 20.Then, the density of the grooves 27 provided in the region D1 is higherthan the density of the grooves 27 provided in the region C1.Specifically, while the regions C1, D1 are both provided with pluralgrooves 27 parallel to each other, the intervals between the grooves 27provided in the region D1 are shorter than the intervals between thegrooves 27 provided in the region C1. In other words, the density of thegrooves 27 per unit area in the region D1 is higher than the density ofthe grooves 27 per unit area in the region C1.

The belt 16 constructed as described above is wrapped around the drivingpulley 5 and the driven pulley 6. While the torque of the drive forcesource 2 is transmitted to the input shaft 7, a clamping force isapplied from the driving pulley 5 and the driven pulley 6 to the belt16. Via contact portions between the driving pulley 5 and elements 18,power transmission is performed in accordance with the friction force,and compression load is applied to the elements 18. The compression loadis transmitted to the elements 18 that are in contact with the drivenpulley 6, via the elements 18 located in a region of the belt 16 that isnot wrapped around either the driving pulley 5 or the driven pulley 6.Due to the friction force between the elements 18 and the driven pulley6, power corresponding to the compression load is transmitted to thedriven pulley 6. In this manner, the torque of the driving pulley 5 istransmitted to the driven pulley 6. Then, the ratio between the rotationspeed of the driving pulley 5 and the rotation speed of the drivenpulley 6, that is, the speed change ratio, is controlled by controllingthe clamping force applied from the driving pulley 5 to the belt 16 soas to control the wrap-around radii of the belt 16 on the driving pulley5 and on the driven pulley 6. Besides, the capacity of the torquetransmitted by the belt type continuously variable transmission 4 iscontrolled by controlling the clamping force applied from the drivenpulley 6 to the belt 16. In this manner, the torque transmitted to theoutput shaft 10 is transmitted to the wheels 3, so that drive force isgenerated.

In regions of the belt 16 that is wrapped around the driving pulley 5and the driven pulley 6 during the torque transmission in the belt typecontinuously variable transmission 4, the elements 18 disposed atadjacent positions rotate relative to each other in a certain anglerange, with a rocking edge (not shown) being a fulcrum, so that eachelement 18 and the inner peripheral surface of each ring 17 slide oneach other. Besides, since the ring 17 is constructed of thesuperimposed annular thin sheets 26, the circumferential speeds of thethin sheets 26 are different and the thin sheets 26 move relative toeach other in the circumferential direction, in regions of the belt 16wrapped on the driving pulley 5 and the driven pulley 6. When thewrap-around radii of the belt 16 on the driving pulley 5 and the drivenpulley 6 is changed through the control of the clamping force appliedfrom the driving pulley 5 and the driven pulley 6 to the belt 16,elements 18 slide along the inclined surfaces of the driving pulley 5and the driven pulley 6. Thus, in the belt type continuously variabletransmission 4, there are sites of heat generation due to the sliding ofvarious component parts on each other. Therefore, lubrication oil issupplied (injected) from the lubrication oil supply device 50 toward thebelt 16, so that these sliding portions are cooled and lubricated. Forexample, in regions of the belt 16 that are not wrapped around thedriving pulley 5 or the driven pulley 6, the lubricating oil is suppliedthereto from above the belt 16 or a side of the belt 16 via an jetnozzle or the like. Incidentally, the lubrication oil is injected to aside of the belt 16 to which a compression force is not applied.Specifically, lubrication oil is injected in a region from a site wherethe belt 16 departs from the driven pulley 6 to a site where the belt 16is wrapped on the driving pulley 5.

Incidentally, in the belt 16, the rings 17 are disposed in thering-receiving portions 23. Therefore, when lubrication oil is supplied,the supplied amount of lubrication oil is different between the entranceside and the interior depth side of each ring-receiving portion 23.Concretely, while a large amount of lubrication oil is supplied to theentrance of each ring-receiving portion 23, a less amount of lubricationoil is supplied to the interior depth side of each ring-receivingportion 23. A reason for this is that since the lubrication oil supplypath (gap) to the interior depth side of each ring-receiving portion 23is narrow, the flow resistance of lubrication oil is strong and alsosince the distance of the path is long, the kinetic energy oflubrication oil declines along the path. Then, the amount of lubricationoil supplied to the gap between the upper end surfaces 24 of eachelement 18 and the rings 17 varies in the width direction of the belt16. Specifically, the amount of lubrication oil supplied to the regionsB1 apart from the neck portion 20 is larger than the amount oflubrication oil supplied to the regions A1 near the neck portion 20.

A case (comparative example) in which the grooves 25 are not providedwill be described. In such a case, the friction coefficient on thecontact surfaces of the upper end surfaces 24 of the elements 18 and theinner peripheral surfaces of the rings 17 has a tendency as shown by adashed line in FIG. 4. Specifically, the friction coefficient shows acharacteristic of diminishing with the increasing distance from the neckportion 20 side toward the driving pulley 5 or the driven pulley 6.Then, the friction force on the contact surfaces of the upper endsurfaces 24 of the elements 18 and the inner peripheral surfaces of therings 17 have a tendency shown by a dashed line in FIG. 5. Specifically,the friction force has a characteristic of declining with the increasingdistance from the neck portion 20 side toward the driving pulley 5 orthe driven pulley 6. Besides, the tension of the each ring 17 as a wholevaries in the width direction thereof. Concretely, as shown by a dashedline in FIG. 6, the tension has a tendency of declining with theincreasing distance from the neck portion 20 side toward the drivingpulley 5 or the driven pulley 6. Due to this tension characteristic, thecircumference of each ring 17 or like also varies in the widthdirection. Concretely, as shown by a dashed line in FIG. 7, the tensionhas a tendency of declining with the increasing distance from the neckportion 20 side toward the driving pulley 5 or the driven pulley 6. Dueto these principles, the movement force of each ring 17 in thecircumferential direction has a characteristic as shown by arrows inFIG. 8. Concretely, the movement force F1 has a characteristic ofdeclining with the increasing distance from the neck portion 20 sidetoward the driving pulley 5 or the driven pulley 6. This results in astate in which a line of the center (not shown) of each ring 17 in thewidth direction during motion is tilted with respect to a line of thecenter (not shown) of the ring 17 in the width direction during a stopof the belt 16. That is, there is a possibility of decline in thecentering performance of each ring 17 within each ring-receiving portion23.

In the first embodiment, however, lubrication oil is discharged (thrownoff) from the contact surfaces of the elements 18 and the rings 17 tothe outside along the grooves 25. This is because the kinetic energy ofthe lubrication oil is less than the kinetic energy of the belt 16.Besides, in the first embodiment, the density of the grooves 25 in theregions B1 is higher than the density of the grooves 25 in the regionsA1. Therefore, although the amount of lubrication oil supplied to theregions B1 is larger than the amount of lubrication oil supplied to theregions A1, the lubrication oil amount discharged from the regions B1 tothe outside along the grooves 25 is larger than the lubrication oilamount discharged from the regions A1 to the outside along the grooves25. Therefore, the lubrication oil amount present in the regions A1 andthe lubrication oil amount present in the regions B1 are substantiallyequal. Hence, the friction coefficient shown in FIG. 4 becomessubstantially constant irrespective of the position in the widthdirection of each ring 17 as shown by a characteristic line representedby a solid line. Furthermore, the friction force shown in the FIG. 5becomes substantially constant irrespective of the position in the widthdirection of each ring 17 as shown by a characteristic line representedby a solid line. The tension of each ring 17 shown in FIG. 6 becomessubstantially constant irrespective of the position in the widthdirection of each ring 17 as shown by a characteristic line representedby a solid line. The circumferential length of each ring 17 becomessubstantially constant irrespective of the position in the widthdirection of each ring 17 as shown by a characteristic line representedby a solid line. Due to the aforementioned operations and characteristiccombined, the movement force of each ring 17 as shown in FIG. 8 becomessubstantially constant irrespective of the position in the widthdirection of each ring 17 as shown by a characteristic line representedby solid lines. Therefore, the centering performance of each ring 17improves.

Furthermore, since the grooves 27 are provided on the inner peripheralsurfaces of the thin sheets 26 constituting each ring 17, lubricationoil is discharged (thrown off) from the contact surfaces of the elements18 and the rings 17 to the outside along the grooves 27. In the firstembodiment, the density of the grooves 27 in the regions D1 is higherthan the density of the grooves 27 in the regions C1. Therefore, due tothe same principles of the discharge of lubrication oil through thegrooves 25, the centering characteristic of the rings 17 improves.

Next, the amount of lubrication oil supplied to gaps between the thinsheets 26 constituting each ring 17. With regard to the gaps between thethin sheets 26, large amounts of lubrication oil are supplied to theentrance of each ring-receiving portion 23, a less amount of lubricationoil is supplied to the interior depth side of each ring-receivingportion 23. A reason for this is as the same as stated above. That is,the amount of lubrication oil supplied to the regions D1 apart from theneck portion 20 is larger than the amount of lubrication oil supplied tothe regions C1 near the neck portion 20. A case (comparative example) inwhich the grooves 27 are not provided will be described. In such a case,the friction coefficient on the contact surfaces of the thin sheets 26has a tendency as shown by the dashed line in FIG. 4. Specifically, thefriction coefficient shows a characteristic of demising with theincreasing distance from the neck portion 20 side toward the drivingpulley 5 or the driven pulley 6. Then, the friction force on the contactsurfaces of the thin sheets 26 have a tendency shown by a dashed line inFIG. 5. Specifically, the friction force has a characteristic ofdeclining with the increasing distance from the neck portion 20 sidetoward the driving pulley 5 or the driven pulley 6. This results in astate in which a line of the center of an inwardly located thin sheet 26in the width direction and a line of the center of an outwardly locatedthin sheet 26 in the width direction are tilted with each other. Thatis, there is a possibility of decline in the centering performance ofeach ring 17 within each ring-receiving portion 23.

In the first embodiment, however, lubrication oil is discharged (thrownoff) from the contact surfaces of the thin sheets 26 to the outsidealong the grooves 25. This is because the kinetic energy of thelubrication oil is less than the kinetic energy of the belt 16. Besides,in the first embodiment, the density of the grooves 27 in the regions D1is higher than the density of the grooves 27 in the regions C1.Therefore, although the amount of lubrication oil supplied to theregions D1 is larger than the amount of lubrication oil supplied to theregions C1, the lubrication oil amount discharged from the region D1 tothe outside along the grooves 27 is larger than the lubrication oilamount discharged from the regions C1 to the outside along the grooves27. Therefore, the lubrication oil amount present in the regions C1 andthe lubrication oil amount present in the regions D1 are substantiallyequal. Hence, the friction coefficient shown in FIG. 4 becomessubstantially constant irrespective of the position in the widthdirection of the thin sheets 26 as shown by the characteristic linerepresented by the solid line. Furthermore, the friction force shown inthe FIG. 5 becomes substantially constant irrespective of the positionin the width direction of the thin sheets 26 as shown by thecharacteristic line represented by the solid line. The tension of thethin sheets 26 shown in FIG. 6 becomes substantially constantirrespective of the position in the width direction of the thin sheets26 as shown by the characteristic line represented by the solid line.The circumferential length of the thin sheets 26 becomes substantiallyconstant irrespective of the position in the width direction of the thinsheets 26 as shown by the characteristic line represented by a solidline. When the friction force in the width direction of the ring 17becomes substantially constant, the tension of the ring 17 issubstantially constant and variation of the stress in the ring 17 isminimized. Then, the durability of the ring 17 is improved.

Due to the aforementioned operations and characteristic combined, themovement force of the thin sheets 26 as shown in FIG. 8 becomessubstantially constant irrespective of the position in the widthdirection of the thin sheets 26 as shown by the characteristic linerepresented by solid lines. Therefore, the centering performance of thethin sheets 26 improves. Incidentally, although in the first embodiment,the grooves 25 and the grooves 27 are both provided, it is permissibleto provide only the grooves 25 or only the grooves 27. It is to be notedherein that the thin sheets 26 correspond to component pieces in theinvention, and the grooves 25, 27 correspond to a lubrication oildischarge mechanism in the invention, and the grooves 27 correspond to afirst groove, and the grooves 25 correspond to a second groove.

Another construction example of the belt 16 will be described inconjunction with a second embodiment, with reference to FIGS. 9 and 10.FIG. 9 is a vertical sectional view (front vertical sectional view) of abelt 16 taken in the thickness direction thereof. FIG. 10 is a partialplan sectional view of the belt 16, viewed from the outer peripheryside. In the second embodiment, the belt 16 has an annular ring 130, andmany elements 131 attached to the ring 130 side by side in thecircumferential direction of the ring 130. The elements 131 will befirstly described. Each element 131 is formed through a press process ofa metal material. The elements 131 are superimposed in the thicknessdirection thereof. Each element 131 has an inward-side portion 132extending in the width direction of the belt 16, a neck portion 133provided continuously from an end of the inward-side portion 132 in thewidth direction and protruded therefrom toward an outer periphery sidein the thickness direction of the belt 16, and a holder portion 134extending from the neck portion 133 in the width direction of the belt16. The inward-side portion 132 and the holder portion 134 extendsubstantially parallel to each other. An opening portion 135 is providedbetween a distal end of the inward-side portion 132 and a distal end ofthe holder portion 134, and a ring-receiving portion 136 is providedbetween the inward-side portion 132 and the holder portion 134. Thering-receiving portion 136 is a space or a recess. The ring-receivingportion 136 is continuous to the opening portion 135.

An upper end surface 137 of the inward-side portion 132 of each element131 is also a bottom surface of the ring-receiving portion 136. Theupper end surface 137 is provided with a lubrication oil dischargemechanism. The lubrication oil discharge mechanism is a mechanism thatdischarges lubrication oil from between the inner peripheral surface ofthe ring 130 and the inward-side portion 132 of the element 131. In thesecond embodiment, grooves 138 are provided as the mechanism. Thegrooves 138 are recesses or dents having a depth in the thicknessdirection of the belt 16, and also are in a checkered pattern formed byintersecting linear grooves 138 with each other in FIG. 10. Besides, asshown in FIG. 10, the density of the grooves 138 is different between aregion E1 and a region F1 that are provided at different positions inthe width direction of the belt 16. The region E1 is a region that isnear the opening portion 135 of the ring-receiving portion 136 in thewidth direction of the belt 16. The region F1 is a region correspondingto a region between the neck portion 133 and the region E1 in the widthdirection of the belt 16. Then, in each upper end surface 137, thedensity of the grooves 138 provided in the region E1 is higher than thedensity of the grooves 138 provided in the region F1. Specifically,while the regions E1, F1 are both provided with plural grooves 138 beingparallel to each other and intersecting with each other, the intervalsbetween the grooves 138 provided in the region F1 are shorter than theintervals between the grooves 138 provided in the region F1. In otherwords, the density of the grooves 138 per unit area in the region E1 ishigher than the density of the grooves 138 per unit area in the regionF1. That is, the area of the grooves 138 per unit area in the region E1is larger than the area of the grooves 138 per unit area in the regionF1.

Both ends of the element 131 in the width direction of the belt 16 havecontact surfaces 139. Each of the two contact surfaces 139 of eachelement 131 is titled with respect to a line of the center (not shown)of the element 139 in the width direction of the belt 16 so that thedistance between the two contact surfaces 22 in the width direction ofthe belt 16 becomes shorter toward an inner periphery side of the belt16. The belt 16 is wrapped around the driving pulley 5 and the drivenpulley 6, and the contact surfaces 139 of the elements 131 contact thedriving pulley 5 and the driven pulley 6 as shown in FIG. 9. One of twoopposite surfaces of the holder portion 134 is provided with twoprotruded pins 140, and the other surface thereof is provided with tworecesses 141. The one and the other of two opposite surfaces of theholder portion 134 mean surfaces thereof in the thickness direction ofeach element 131. When the elements 131 are superimposed on one anotherin the thickness direction, the pins 140 of the elements 131 aredisposed in the recesses 141 of the adjacent elements 131, whereby theelements 131 disposed at adjacent positions are defined in positionrelative to each other, concretely, defined in position relative to eachother on a plane orthogonal to the stacking direction of the elements131.

Next, a construction of the single ring 130 disposed in thering-receiving portion 136 will be described. The ring 130 isconstructed by layering a plurality of metal-made annular thin sheets142 on each other's inner and outer peripheries, that is, in theinner-to-outer periphery direction. That is, the thin sheets 142 aresuperimposed on one another in the thickness direction to construct aring 130. Besides, the thin sheets 142 in the superimposed state areslidable relative to one another in the circumferential direction.Besides, the thin sheets 142 have the same width in the width directionof the belt 16. In the width direction of the belt 16, the width of thering 130 is narrower than the width of the ring-receiving portion 136.Therefore, when the ring 130 is disposed in the ring-receiving portion136 of each element 131, that is, when the elements 131 are attached tothe ring 130 to assemble the belt 16, and the belt 16 is wrapped aroundthe driving pulley 5 and the driven pulley 6, the inward-side portion132 contacts the inner peripheral surface of the ring 130, so as toprevent the elements 131 from falling apart from the ring 130.

At least one of an inner peripheral surface and an outer peripheralsurface of each of thin sheets 142 that constitute the ring 130 isprovided with grooves 143 as a lubrication oil discharge mechanism asshown in FIG. 10. The grooves 143 are recesses or dents having a depthin the thickness direction of each thin sheet 142. In FIG. 10, thegrooves 143 are provided on the outer peripheral surface of each thinsheet 142 as an example construction. Concretely, a checkered pattern isformed by intersecting linear grooves 143 with each other. Besides, asshown in FIG. 10, the density of the grooves 143 is different between aregion G1 and a region H1 that are disposed at different positions oneach thin sheet 143 in the width direction of the belt 16. It is to benoted herein that the region G1 is a region closer to the neck portion133 in the width direction of the belt 16. Besides, the region H1 iscloser to the opening portion 135 than the region G1 is. That is, in thewidth direction of the belt 16, the region H1 occupies a position thatis more apart from the neck portion 133 than the region G1 is from theneck portion 133. Then, the density of the grooves 143 provided in theregion H1 is higher than the density of the grooves 143 provided in theregion G1. Specifically, while the regions G1, H1 are both provided withplural grooves 143 parallel to each other, the intervals between thegrooves 143 provided in the region H1 are shorter than the intervalsbetween the grooves 143 provided in the region G1. In other words, thedensity of the grooves 143 per unit area in the region H1 is higher thanthe density of the grooves 143 per unit area in the region G1. That is,the area of the grooves 143 per unit area in the region H1 is designedto be larger than the area of the grooves 143 per unit area in regionG1.

In the belt 16 in the second embodiment, as in the first embodiment, thetorque of the driving pulley 5 is converted into compression forcebetween the elements 131, and the compression force is transmitted tothe driven pulley 6, so that torque in such a direction as to rotate thedriven pulley 6 is generated. When torque is being transmitted, elements131 disposed at adjacent positions rotate relative to each other in acertain angle range, with a rocking edge (not shown) being a fulcrum, sothat each element 131 and the inner peripheral surface of the ring 130slide on each other. Besides, the ring 130 is constructed ofsuperimposing annular thin sheets 142 on one another, and the thinsheets 142 slid on each other due to the same principle as in the firstembodiment. In the second embodiment, too, the elements 131 slide alongthe inclined surfaces of the driving pulley 5 and the driven pulley 6,by substantially the same principle as in the first embodiment. Then, inthe second embodiment, similarly to the first embodiment, the belt 16 issupplied with lubrication oil, so that the cooling and lubrication ofsliding portions of the belt 16 is performed.

In the second embodiment, when the belt 16 shown in FIG. 9 is suppliedwith lubrication oil from above, the lubrication oil passes through theopening portion 135 of each element 131, and is supplied into thering-receiving portion 136 thereof. The amount of lubrication oilsupplied in the ring-receiving portion 136 varies in the width directionof the ring 130. Concretely, a large amount of lubrication oil issupplied to a vicinity of the opening portion 135, whereas a less amountof lubrication oil is supplied to the neck portion 133. A reason forthis is that since the lubrication oil supply path (gap) to the neckportion 133 of each element 131 is narrow, the flow resistance oflubrication oil is strong, and also since the distance of the path islong, the kinetic energy of lubrication oil declines along the path. Inthe second embodiment, however, the density of the grooves 138 is higherin the region E1 than in the region F1. That is, the lubrication oildischarging function is higher in the region E1 than in the region F1.As a result, the friction coefficients and the friction forces on thecontact surfaces between the upper end surface 137 of each element 131and the inner peripheral surface of the ring 130 become substantiallyequalized or uniform in the width direction of the ring 130. Therefore,the centering performance of the ring 130 improves. Furthermore, whenthe friction force in the width direction of the ring 130 becomessubstantially constant, the tension of the ring 130 is substantiallyconstant and variation of the stress in the ring 130 is minimized. Then,the durability of the ring 130 is improved.

Next, the amount of lubrication oil supplied to gaps between the thinsheets 142 constituting the ring 130. In each of the gas between thethin sheets 142, the amount of lubrication oil supplied varies in thewidth direction of the ring 130 for substantially the same reason asdescribed above. That is, the amount of lubrication oil supplied to theregion H1 apart from the neck portion 133 is larger than the amount oflubrication oil supplied to the region G1 closer to the neck portion133. In the second embodiment, however, lubrication oil is discharged(thrown off) from the contact surfaces of the thin sheets 142 along thegrooves 143. The lubrication oil present in the region G1 is dischargedafter passing through the region H1. Besides, the lubrication oil in theregion H1 is discharged without any special process. The lubrication oildischarged into the ring-receiving portions 136 of the elements 131 isdischarged into an external space through the gaps between the elements131. The density of the grooves 143 in the region H1 is higher than thedensity of the grooves 143 in the region G1. That is, the lubricationoil discharging function in the region H1 is higher than the lubricationoil discharging function in the region G1. Therefore, the lubricationoil amount present in the region H1 and the lubrication oil amountpresent in the region G1 become substantially equalized, and thefriction coefficient and the friction force on the contact surfaces ofthe thin sheets 142 become substantially equalized in the widthdirection of the ring 130. Therefore, the centering performance of thethin sheet 142 improves. In addition, although in the second embodiment,the grooves 138 and the grooves 143 are both provided, it is permissibleto provide only the grooves 138 or only the grooves 148. It is to benoted herein that the thin sheet 142 corresponds to a component piece inthe invention, and the grooves 138, 143 correspond to a lubrication oildischarge mechanism in the invention, and the grooves 143 correspond toa first groove, and the grooves 138 correspond to a second groove.

Next, the belt 16 will be further described in conjunction with a thirdembodiment with reference to FIG. 11. The third embodiment correspondsto claims 5 and 6. FIG. 11 is a vertical sectional view (front sectionalview) of a belt 16 in the thickness direction. In the illustration ofthe third embodiment, the same constructions as those described inconjunction with the first embodiment will be assigned with the samereference characters as in the first embodiment. In the thirdembodiment, the grooves 25 and the grooves 27 described in conjunctionwith the first embodiment are both discarded. In the third embodiment,two upper end surfaces 24 of each element 18 are provided with grooves60 that extend in the circumferential direction of the belt 16. Eachupper end surface 24 is partitioned in the width direction of the ring17 into a region J1 and a region K1 by the groove 60. The region J1 isnear the neck portion 20, and the region K1 is apart from the neckportion 20. In a plane where the belt 6 is viewed from the outerperiphery side, the area of the region J1 is smaller than the area ofthe region K1. Concretely, the effective area of the region J1 thatcontacts the inner peripheral surface of each ring 17 is smaller thanthe effective area of the region K1 that contacts the inner peripheralsurface of each ring 17.

Operation of the third embodiment will be described. Similarly to thefirst embodiment, lubrication oil enters a gap between the ring 17 andthe upper end surface 24. Concretely, the region K1 is supplied withlubrication oil. Since the groove 60 are provided, the lubrication oilis discharged via the grooves 60. That is, the region J1 is not suppliedwith lubricant oil, or is supplied with a reduced amount of lubricantoil. Therefore, the friction coefficient in the region K1 becomessmaller than the friction coefficient in the region J1. In contrast, thearea of the region J1 is smaller than the area of the region K1. Then,the friction force found from the friction coefficient, the area, etc.becomes substantially constant at different positions in the widthdirection of the ring 17, that is, between the region J1 and the regionK1, so that the decline in the centering performance of the ring 17 canbe restrained. Furthermore, when the friction force in the widthdirection of the ring 17 becomes substantially constant, the tension ofthe ring 17 is substantially constant and variation of the stress in thering 17 is minimized. Then, the durability of the ring 17 is improved.It is to be noted herein that the grooves 60 and the regions K1, J1constructed in accordance with the foregoing area relationshipcorrespond to a friction force equalization mechanism, and the grooves60 correspond to a partition groove, and the region J1 corresponds to afirst region in the invention, and the region K1 corresponds to a secondregion in the invention.

Next, a fourth embodiment of the belt 16 will be described withreference to FIG. 12. FIG. 12 is a sectional view of a belt 16 in itsthickness direction. In the fourth embodiment, the belt 16 has anannular ring 30, and many elements 31 attached to the ring 30 side byside in the circumferential direction of the ring 30. The elements 31will be firstly described. The elements 31 are formed through a pressprocess of a metal material. The elements 31 are superimposed on eachother in the thickness direction thereof. Each element 31 has a baseportion 32 that is extended in the width direction of the belt 16, andtwo neck portions 33 that are continuous from two opposite ends of thebase portion 32 in the thickness direction thereof and that areprotruded to an outer periphery side in the thickness direction of thebelt 16. Thus, two neck portions 33 are provided on the two oppositeends of each element 31 in the width direction of the belt 16. Each neckportion 33 is provided with a holder portion 34 protruded toward theother neck portion 33. In this manner, an opening portion 35 is providedbetween the holder portions 34, and a ring-receiving portion 36 isprovided, surrounded by the two holder portions 34, the two neckportions 33 and the base portion 32. The ring-receiving portion 36 is aspace or a recess. The ring-receiving portion 36 is continuous with theopening portion 35. In the width direction of the belt 16, the width ofthe ring-receiving portion 36 is larger than the opening width of theopening portion 35. The ring 30 is disposed in the ring-receivingportion 36.

An upper end surface 37 of the base portion 32 of each element 31 isalso a bottom surface of the ring-receiving portion 36. The upper endsurface 37 is provided with two grooves 61 extending along thecircumferential direction of the belt 16. The grooves 61 are provided atdifferent positions in the width direction of the belt 16. Thus, theupper end surface 37 is partitioned into two regions L1 and one regionM1 in the width direction of the ring 30. It is to be noted herein thatthe two regions L1 are near the neck portion 33, and the region M1 isdisposed between the regions L1 and is apart from the neck portion 33.The area of the region M1 is smaller than the area of either one of theregion L1. More specifically, in terms of the effective area thatcontacts the inner peripheral surface of the ring 30, the region M1 issmaller than the area of either one of the regions L1.

Operation of the fourth embodiment will be described. Lubrication oilenters a gap between the upper end surface 37 and the ring 30 via theopening portion 35. Concretely, lubrication oil is supplied to theregions L1, and is discharged along the grooves 61. That is, the regionM1 is not supplied with lubrication oil, or is supplied with only areduced amount of lubrication oil. Therefore, the friction coefficientof the region M1 is greater than the friction coefficient of either oneof the regions L1. The area of the region M1 is smaller than the area ofthe region L1. Then, the friction force found from the frictioncoefficient, the area, etc. becomes substantially equal in the widthdirection of the ring 30, and restrains the decline in the centeringperformance of the ring 30. Furthermore, when the friction force in thewidth direction of the ring 30 becomes substantially constant, thetension of the ring 30 is substantially constant and variation of thestress in the ring 30 is minimized. Then, the durability of the ring 30is improved. Incidentally, the grooves 61 correspond to a friction forceequalization mechanism and to a partition groove. The region M1corresponds to an inner-side region in the invention, and the regions L1correspond to an outer-side region in the invention.

Next, a fifth embodiment in conjunction with the belt type continuouslyvariable transmission 1 will be described with reference to FIGS. 2, 13,14 and 15. FIG. 13 is a vertical sectional view (front verticalsectional view) of the belt 16 in the thickness direction. FIG. 14 is apartial plan view of the belt 16 viewed from an outer periphery side.FIG. 15 is a partial side view of the belt 16. In the fifth embodiment,the belt 16 has two ring-receiving portions 23, and two rings 17disposed in the ring-receiving portions 23, similar to the beltsdescribed above in conjunction with the first embodiment and the thirdembodiment. An air blowing mechanism 70 is provided between a drivingpulley 5 and a driven pulley 6. The air blowing mechanism 70 is a devicethat blows air to the belt 16 so as to generate a force that pushes thelubrication oil located between thin sheets 26 constituting the rings17, or the lubrication oil located between the rings 17 and the elements18, to a region (location or site) that is as near to the neck portion20 as possible. The air blowing mechanism 70 has an air compressor (notshown), an angle adjustment mechanism, a valve (not shown), air jetnozzles 71, etc. Each air jet nozzle 71 is disposed on the movement pathof the belt 16 between the lubrication supply position of a lubricationoil supply mechanism 50 and the position at which the belt 16 winds onthe driving pulley 5. The air jet nozzles 71 are disposed on both sidesacross the movement path of the belt 16. A distal end of each air jetnozzle 71 is directed toward an adjacent one of the rings 17 of the belt16. Besides, in the thickness direction of the belt 16, the distal endsof the air jet nozzles 71 are disposed at the same position (height) asthe ring-receiving portions 23 and the rings 17, as shown in FIGS. 13and 15.

The air blowing mechanism 70 is constructed so as to be controlled bythe electronic control device 100 and be adjustable in the air jettiming, the jet pressure, the jet amount, the jet speed, the jet angle(direction), etc. The angle adjustment mechanism has an actuator, forexample, a step motor. The jet angle means an angle formed between aline of the center in the width direction of the belt and an air jetcenter line, and an angle formed between a line of the center in thethickness direction of the rings and the air jet center line. The valveis constructed of, for example, a solenoid valve. By adjusting theelectrification current, the electrification timing, the degree ofopening, etc., the valve can be controlled in the timing of air jet fromthe air jet nozzles 71, the jet amount, the jet pressure, the jet speed,etc.

As described above, lubrication oil is supplied from the lubrication oilsupply mechanism 50 to the belt 16. In the belt 16 constructed as shownin FIG. 13, each element 18 is provided with the ring-receiving portions23 that each have an interior depth in the width direction of the belt16, and the rings 17 are disposed in the ring-receiving portions 23.Therefore, the amount of lubrication oil is large in the vicinity of anentrance of each ring-receiving portion 23, and the flow resistance oflubrication oil is high and therefore the amount of lubrication oil isless in the vicinity of an interior depth side of each ring-receivingportion 23. In the fifth embodiment, however, when air is injected fromthe air jet nozzles 71, the lubrication oil in the vicinity of theentrance of each ring-receiving portion 23 is pushed by the air jetpressure toward the interior depth side of the ring-receiving portion23. Therefore, in the width direction of the rings 17, the amount oflubrication oil present between the upper end surfaces 24 of eachelement 18 and the inner peripheral surfaces of the rings 17 and theamount of lubrication oil present between the thin sheets 26constituting the rings 17 become substantially equalized or uniform.Therefore, substantially the same effects as in the first embodiment canbe attained.

Incidentally, the belt 16 applied in the fifth embodiment may also be abelt that is not provided with any of the grooves 25, 27, 60, or mayalso be a belt that is provided with at least one of the grooves 25, 27,60. Besides, the position at which the air jet nozzles 71 is disposedmay be in a region in which compression load occurs between the elements16. That is, it suffices that the air jet nozzles 71 are able to injectair toward the belt 16 after lubrication oil has been supplied to thebelt 16. Specifically, the air jet nozzles 71 are disposed in a regionwhere the belt 16 is not wrapped around either one of the driving pulley5 and the driven pulley 6.

1. A continuously variable transmission belt that has rings eachconstructed by superimposing annular component pieces on each other'sinner and outer peripheries, and a plurality of elements stacked in acircumferential direction of the rings and attached to the rings,wherein each of the elements is provided with a neck portion extendingin a radius direction of the rings, and each of the elements is providedwith two ring-receiving portions on two opposite sides of the neckportion in a width direction of the rings, and the rings are disposed inthe two ring-receiving portions, respectively, and the elements contacta driving pulley and a driven pulley, characterized by comprising alubrication oil discharge mechanism that discharges out a lubricationoil that is in at least one of a gap between the annular componentpieces, and a gap between each ring and the elements, and thelubrication oil discharge mechanism has a construction in which afunction of discharging the lubrication oil present in a region that isremote from the neck portion in a width direction of the rings is higherthan a function of discharging the lubrication oil present in a regionthat is near the neck portion in the width direction of the rings. 2.The continuously variable transmission belt according to claim 1,characterized in that: the lubrication oil discharge mechanism has afirst groove provided on each of an inner periphery and an outerperiphery of the annular component pieces, and a second groove providedon each of the elements; and the function of discharging the lubricationoil present in the region that is remote from the neck portion in thewidth direction of the rings is made higher than the function ofdischarging the lubrication oil present in the region that is near theneck portion in the width direction of the rings by, in a plane on therings viewed from an outer periphery side or an inner periphery side,making an area of the first groove present in the region that is remotefrom the neck portion in the width direction of the rings larger thanthe area of the first groove present in the region that is near the neckportion in the width direction of the rings; and the function ofdischarging the lubrication oil present in the region that is remotefrom the neck portion in the width direction of the rings is made higherthan the function of discharging the lubrication oil present in theregion that is near the neck portion in the width direction of the ringsby, in the plane on the rings viewed from the outer periphery side orthe inner periphery side, making the area of the second groove presentin the region that is remote from the neck portion in the widthdirection of the rings larger than the area of the second groove presentin the region that is near the neck portion in the width direction ofthe rings.
 3. A continuously variable transmission belt that has a ringconstructed by superimposing annular component pieces on each other'sinner and outer peripheries, and a plurality of elements stacked in acircumferential direction of the ring and attached to the ring, whereineach of the elements is provided with an inward-side portion and aholder portion extending in a width direction of the ring from a neckportion extending in a radius direction of the ring, and each of theelements is provided with a ring-receiving portion between theinward-side portion and the holder portion in the width direction of thering, and the ring is disposed in the ring-receiving portion, and theelements contact a driving pulley and a driven pulley, characterized bycomprising a lubrication oil discharge mechanism that discharges out alubrication oil that is in at least one of a gap between the annularcomponent pieces, and a gap between the ring and the elements, and thelubrication oil discharge mechanism has a construction in which afunction of discharging the lubrication oil present in a region that isremote from the neck portion in a width direction of the ring is higherthan a function of discharging the lubrication oil present in a regionthat is near the neck portion in the width direction of the ring.
 4. Thecontinuously variable transmission belt according to claim 3,characterized in that: the lubrication oil discharge mechanism has afirst groove provided on each of an inner periphery and an outerperiphery of the annular component pieces, and a second groove providedon each of the elements; and a function of discharging the lubricationoil present in the region that is remote from the neck portion in thewidth direction of the ring is made higher than the function ofdischarging the lubrication oil present in the region that is near theneck portion in the width direction of the ring by, in a plane on thering viewed from an outer periphery side or an inner periphery side,making an area of the first groove present in the region that is nearthe neck portion in the width direction of the ring smaller than an areaof the first groove present in the region that is remote from the neckportion in the width direction of the ring; and the function ofdischarging the lubrication oil present in the region that is near theneck portion in the width direction of the ring is made higher than thefunction of discharging the lubrication oil present in the region thatis remote from the neck portion in the width direction of the ring by,in the plane on the ring viewed from the outer periphery side or theinner periphery side, making an area of the second groove present in theregion that is near the neck portion in the width direction of the ringsmaller than an area of the second groove present in the region that isremote from the neck portion in the width direction of the ring.
 5. Acontinuously variable transmission belt that has a ring constructed bysuperimposing annular component pieces on each other's inner and outerperipheries, and a plurality of elements stacked in a circumferentialdirection of the ring and attached to the ring, wherein each of theelements is provided with a ring-receiving portion, and the ring isdisposed in the ring-receiving portion, and the elements contact adriving pulley (5) and a driven pulley, characterized by comprising afriction force equalization mechanism that makes a friction force thatoccurs due to contact between a bottom surface that constitutes thering-receiving portion and an inner peripheral surface of the ringuniform in the width direction of the ring.
 6. The continuously variabletransmission belt according to claim 5, characterized in that: each ofthe elements is provided with a neck portion extending in a radiusdirection of the ring, and each of the elements is provided with tworing-receiving portions on two opposite sides of the neck portion in thewidth direction of the rings, and the ring is disposed in each of thetwo ring-receiving portions, and the bottom surface of each of the tworing-receiving portions and the inner peripheral surface of acorresponding one of the rings contact each other; and the frictionforce equalization mechanism is a partition groove that partitions eachbottom surface into a first region near to the neck portion and a secondregion apart from the neck portion, and that prevents the lubricationoil from reaching the first region via the second region, and an area ofthe first region is smaller than the area of the second region.
 7. Thecontinuously variable transmission belt according to claim 5,characterized in that each of the elements is provided with two neckportions extending in a radius direction at different positions in thewidth direction of the ring, and a ring-receiving portion is providedbetween the two neck portions, and the ring is disposed in thering-receiving portion, and a bottom surface constituting thering-receiving portion and the inner peripheral surface of the ringcontact each other; and the friction force equalization mechanism is apartition groove that partitions each bottom surface into two outer-sideregions near to the neck portion and an inner-side region apart from theneck portion, and that prevents the lubrication oil from reaching theinner-side region via the outer-side regions, and an area of theinner-side region is smaller than the area of one of the outer-sideregions.
 8. A continuously variable transmission that has a drivingpulley, a driven pulley, and a continuously variable transmission beltwrapped around the driving pulley and the driven pulley, wherein thecontinuously variable transmission belt has rings each constructed bysuperimposing annular component pieces on each other's inner and outerperipheries, and a plurality of elements stacked in a circumferentialdirection of the rings and attached to the rings, and each of theelements is provided with a neck portion extending in a radius directionof the rings, and each of the elements is provided with tworing-receiving portions on two opposite sides of the neck portion in awidth direction of the rings, and the rings are disposed in the tworing-receiving portions, respectively, characterized by comprising anair blowing mechanism that blows air toward the ring-receiving portionsto move a lubrication oil present in each ring-receiving portion to aninterior depth side of the ring-receiving portion so that in a plane onthe continuously variable transmission belt viewed from an outerperiphery side or an inner periphery side, a difference between afriction force on mutual contact portions of the component pieces in aregion that is near the neck portion in the width direction of thecontinuously variable transmission belt or a friction force that occurson contact portions between an inner peripheral surface of each ring andthe elements, and a friction force on mutual contact portions of thecomponent pieces in a region that is apart from the neck portion in thewidth direction of the continuously variable transmission belt or afriction force that occurs on contact portions between the innerperipheral surface of each ring and the elements is made small.
 9. Thecontinuously variable transmission according to claim 8, characterizedin that the continuously variable transmission belt wrapped around thedriving pulley and the driven pulley is provided with a lubrication oilsupply device that supplies the lubrication oil, between the drivingpulley and the driven pulley, and the air blowing mechanism is providedrearward of the lubrication oil supply device in a rotation direction ofthe continuously variable transmission belt.
 10. The continuouslyvariable transmission according to claim 9, characterized in that thelubrication oil supply device and the air blowing mechanism arepositioned between a point where the continuously variable transmissionbelt comes out of a wrapping on the driven pulley and a point where thecontinuously variable transmission belt becomes wrapped on the drivingpulley, and supplies the lubrication oil and blows air.